Vehicles, such as cars and motorcycles, have a power transmission system which is able to provide controlled application of the power according to the driving condition. Generally, the term transmission refers to the whole drivetrain, including clutch actuator, gearbox and other essential components. The clutch actuator acts as a link between the gearbox and the pedal, allowing the rider or driver to engage the gears during riding or driving.
An automatic transmission is a type of vehicle transmission that can automatically change gear ratios as speed and throttle position varies. It is convenient to operate the vehicles but also might be dangerous in some circumstances. For example, while the vehicle is taking a sharp turn on the road, an unexpected gear shifting may easily cause the vehicle to slip or roll over.